import sys

# import some PyQt5 modules
from PyQt5.QtWidgets import QApplication
from PyQt5.QtWidgets import QWidget
from PyQt5.QtGui import QImage
from PyQt5.QtGui import QPixmap
from PyQt5.QtCore import QTimer

# import Opencv module
import cv2

from Ui_untitled import *

class MainWindow(QtWidgets.QMainWindow):
    # class constructor
    def __init__(self):
        # call QWidget constructor
        super().__init__()
        self.ui = Ui_MainWindow()
        self.ui.setupUi(self)
        self.ui.pushButton_2.clicked.connect(QtWidgets.qApp.quit)

if __name__ == '__main__':
    app = QApplication(sys.argv)

    # create and show mainWindow
    mainWindow = MainWindow()
    mainWindow.show()
    sys.exit(app.exec_())